A male longhorn moth, probably Adela reaumurella (Lepidoptera: Adelidae). One of several that I saw on my walk round the lakes on on Saturday. Photo taken in Whiteknights Park, Reading University grounds, Reading, UK, on 2011-04-09.
On the following afternoon I saw several several swarms of these moths on a walk to Mapledurham. The swarms seemed to consist of only males, all vigorously twirling their long antennae. I did see one female (much shorter antennae and a greenish-gold sheen rather than a silvery black - see here) but it was by itself down in the undergrowth, well away from the swarms. Photo taken in Chazey Wood, near Caversham, UK, on 2011-04-10.